I am developing an app in ddd maner. So I have a complex domain model. Suppose I have a Fare object and Airline. Each Airline should contain several or much more Fares.

My UI should represent Model (only small part of complex model) as a list of Airline, when the user select the Airline, I must show the list of Fares. User can filtering the Fares (by travel time, cost, etc.).

What is the appropriate place for filtering Fares and Airlines?

I am assuming that I should do it in ViewModel. Like: My domain model has wrapped with Service Layer -> UI works with ViewModel -> ViewModel obtain data from Service Layer filtering it and create DTO objects for UI. Or I'm wrong?